Tremie Concrete Placement

Tremie concrete placement uses a pipe through which concrete is placed below water. Tremie pipe is also used to place concrete that would otherwise fall a great distance from the concrete discharge point at the top of the shaft to the concrete placement point at the bottom of the shaft

What Is Honeycomb in Concrete | Cause of Honeycomb in Concrete| Cure of Honeycomb in Concrete

Table of Contents

What Is Honeycomb In Concrete?

This takes place when the mortar doesn’t fill the distance between the coarse aggregate particles. The presence of honeycomb indicates that the first stage of consolidation hasn’t yet been completed at these locations.

Where it shows on the surface, it is necessary to chip out the area and make a repair. Such repairs must be kept to a minimum, mainly because they mar the appearance of the structure.

Honeycomb is caused by using faulty or improper vibrators or by poor vibration Processes. Unsystematic insertions at haphazard angles will cause an accumulation of mortar on the surface while the lower portion of the layer may be under-vibrated.

Sometimes, there are other factors contributing to honeycombs, such as insufficient paste to fill the voids between the aggregate, improper ratio of sand to total aggregate, poor aggregate grading.

improper ratio of sand to total aggregate, improper workability for the placing conditions or insufficient clearance between the reinforcing steel.

In setting steel spacing, both the designer and the builder should keep in mind that the concrete must be consoled.

Honeycomb is a void left in concrete due to the failure of the mortar to effectively fill the spaces among coarse aggregate particles.

Rock pockets are generally severe conditions of a honeycomb where an excessive volume of aggregate is found.

Also Read: All About Roller Compacted Concrete | What Is Roller Compacted Concrete | Roller Compacted Concrete Process

Cause of Honeycomb In Concrete

Primary Causes of Honeycomb

1. Design of Members

Highly Congested Reinforcement
Narrow Section
Internal Interference
Reinforcement Splices

2. Forms

Leaking at Joints
Severe Grout Loss

3. Construction Conditions

Reinforcement Too Close to Forms
High-Temperature
Accessibility

4. Properties of Fresh Concrete

Insufficient Fines
Early Stiffening
Excessive Mixing
Aggregate That Is Too Large

5. Placement

Excessive Free-Fall
Excessive Travel in Forms
Lift That Is Too High
Improper Tremie or Drop Chute
Segregation

Also Read: All About M Sand | What Is M Sand | Properties of Manufactured Sand | Advantages & Disadvantages of Manufactured Sand

6. Consolidation

Vibrator Too Small
Frequency Too Low
Amplitude Too Small
Short Immersion Time
Excessive Spacing Between Insertion
Inadequate Penetration

Cure for Honeycombs in Concrete

Corrosion is a process that continues through reinforcement rods even into good concrete. This results in losing grip between concrete and sticks, which is very dangerous to the safety and life of concrete structures. Concrete fall should be kept to a minimum.

Honeycombs as a defect not only reduce the load-bearing capacity of concrete; however, water finds a simple method to reinforce rods and rusting, and corrosion starts.

Corrosion is a process that lasts through reinforcement rods even in good concrete, this result in dropping the grip between concrete and sticks that’s very dangerous to the safety and life of concrete structures

Strictly speaking, where honeycombs are detected in concrete, the affected area ought to be broken, and also the portion ought to be reconsecrated after applying grouting chemicals to the old surface.

Honeycombs as a defect not only reduce the load-bearing capacity, but water finds a simple method to reinforce, corrosion, and rods rusting tarts.

In the case of honeycombs on surface pressure grouting with cement-based chemicals that are non-shrinkable Could be adopted after taking the opinion of This designer and acting According to his advice.

Taping with a wooden hammer, the sides of shuttering from outside through concreting and moving will assist in minimizing honeycombs to a great extent in the event of beams and columns.

At places of the junction of beams and columns concrete with strictly 20mm and down aggregates must be used with slightly more cement and water to avoid honeycombs.

The use of a thinner needle says 25mm or less with a vibrator at intricate places of concreting will also help in reducing honeycombs.

Also Read: All About Reinforced Brick Masonry | What Is Reinforced Brick Masonry | Construction of the Reinforced Brick wall

Types of Grouting

5 Diffrent types of Grouting Method

Jet Grouting
Fracture Grouting
Permeation Grouting
Compaction Grouting
Vacuum Grouting

1. Jet Grouting

Jet grouting uses a high-pressure ‘jet’ force applied of either grout, air, water, or a combination to erode soil whilst simultaneously injecting grout into the soil through a ‘jet monitor.’

The specially designed monitor and drill stem are rotated and raised at the same time to combine the grout with the original soil to form ‘silcrete.’

The end product is cemented round columns and is basically effective in any soil but not necessarily efficient in every soil.

2. Fracture Grouting

This method uses a low-viscosity grout that splits through the ground by penetrating and hydraulic fracturing into the fractures.

The in situ soils are soil displaced immediately next to the fractures and are densified, but to a lesser extent than compaction grouting.

This grouting can also be referred to as compensation grouting and is commonly used to relevel structures.

3. Permeation Grouting

Permeation grouting also called penetration grouting, is the most common and conventional grouting approach. It involves filling any joints, cracks, or voids as in rock, soil, concrete, and other porous materials.

This method’s idea is to fill a void without displacing the formation or creating some change in quantity or configuration from the medium. It is done to strengthen the present formation, creating a water-impermeable barrier, or even both.

There are two forms of permeation injection grout systems: a circulating grout system and also a direct grout system.

4. Compaction Grouting

Compaction Grouting involves an injection grouting of low mobility grout using drill casings that are drilled to pre-set depths.

The grout, usually comprised of sand, cement, water, and fly ash, is placed from the bottom up with pressure-based criteria.

After each consecutive stage, this drill casing is lifted upward until it is entirely taken out. Compaction Grouting is also commonly called Low Mobility Grouting.

5. Vacuum Grouting

This type of grouting to a user in honeycomb time. Vacuum grout sends precise cement salary in concrete.

Interestingly, although grout is typically propelled by pressure, if a void is placed under pressure, then the grout can be ‘sucked’ this is known as vacuum grouting.

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What Is Honeycomb in Concrete

This bumpy condition is often referred to as concrete honeycombing and causes broken bits of rock and stone on the edges of a concrete slab. While it’s not always common, it’s usually a result of voids in concrete due to the mortar not filling the spaces between coarse particles

What Causes Honeycombing in Concrete

Typically, concrete honeycombing can be caused by a range of factors, but the most common include weak compaction and holes/gaps in the formwork. Weak compaction causes the mortar to fill voids between the coarse aggregate. Holes and gaps, on the other hand, allow mortar to drain out of the concrete

What Is Concrete Honeycombing

Honeycombing is the term used to describe areas of the surface that are coarse and stony. It may be caused by insufficient fine material in the mix, perhaps due to incorrect aggregate grading or poor mixing.

Honeycomb in Concrete

Honeycomb is a rough and stony surface that appears on concrete when there are air voids between the course and the aggregate. This happens when insufficient fine material gets into the concrete mixture due to poor mixing or incorrect aggregate grading

Honeycombing in Concrete Is Caused Due To

Effects of Honeycomb in Concrete

In general, concrete honeycombing is considered a cosmetic condition that can only be found on the exterior areas of the concrete pour. However, if left untreated over a long period of time, moisture could penetrate the exposed areas. This could cause serious structural conditions, including concrete cancer.

Patching Honeycomb Concrete

Isolate the affected area by removing layers of honeycombing until suitable concrete is exposed
Thoroughly clean the area to be repaired and remove all dirt and loose aggregate
Wet the cleaned area prior to applying non-shrink grout
Texture and colour should then be matched for aesthetic finish

Types of Honeycomb in Concrete

There are three types of honeycomb in concrete, such as,

Small sized honeycomb.
Medium sized honeycomb.
Large sized honeycomb.

Cause of Honeycomb in Concrete

This happens when insufficient fine material gets into the concrete mixture due to poor mixing or incorrect aggregate grading

Construction Conditions

General conditions are an integral part of the construction contract. They consist of items and resources needed for project completion that will not be part of the finished product that is turned over to the owner.

Site Conditions in Construction

soil with inadequate bearing capacity to support the building being constructed, soil that cannot be reused as structural fill, unanticipated groundwater, quicksand, mud, rock formations, or other artificial subsurface obstructions

Supplementary Conditions Construction

Supplementary Conditions are modifications to the General Conditions—additions, deletions, changes. This is as the term is defined by EJCDC and the Construction Specification Institute (CSI)

Unknown Site Conditions in Construction

Construction agreement definitions differ, yet generally an unforeseen site condition takes place when the owner as well as contractor at the time of the contract finalizing are unaware that the subsurface of a construction site has a physical property or does not have a physical property presumed to be existing

Adverse Weather Conditions Construction

Adverse Weather is defined as the occurrence of one or more of the following conditions within a twenty-four (24) hour day that prevents construction activity exposed to weather conditions or access to the site: Precipitation (rain, snow, or ice) in excess of one-tenth inch (0.10”) liquid measure.

Ground Conditions in Construction

“Ground conditions” means the ability of the ground to support the equipment (including slope, compaction, and firmness). “Supporting materials” means blocking, mats, cribbing, marsh buggies (in marshes/wetlands), or similar supporting materials or devices

Properties of Fresh Concrete

Workability.
Segregation.
Bleeding.
Plastic shrinkage.
Setting.
Temperature.
Water Cement Ratio.

Workability of Fresh Concrete

Workability of Concrete is a broad and subjective term describing how easily freshly mixed concrete can be mixed, placed, consolidated, and finished with minimal loss of homogeneity.

Density of Fresh Concrete

Concrete made using normal-weight aggregate commonly has a density of approximately 150 pounds per cubic foot.

Fresh Concrete and Hardened Concrete

Once the mixing was completed the mixture is said to be Fresh concrete which is in plastic state and can be moulded in any forms whereas the Hardened concrete is the one which is fully cured.

Rheology of Fresh Concrete

The rheology of fresh concrete like workability includes the parameters of stability, mobility and compactability. Rheological concepts can also be used to describe the mechanical behaviour of solidified cement paste, which shows both elastic and inelastic deformations.

Air Content in Fresh Concrete

A typical air content for concrete with a ¾-inch maximum-size aggregate is about 6%, and specified ranges in air content are typically minus 1 ½% and plus 1 ½% of the target value.

Concrete Properties

Mechanical strength, in particular compressive strength. The strength of normal concrete varies between 25 and 40 MPa
Durability
Porosity and density
Fire resistance
Thermal and acoustic insulation properties
Impact resistance

Dowel Bar Placement in Concrete Pavement

Dowel bars are typically placed at the mid-depth of the slab and should be parallel to the pavement surface and parallel to the direction of travel. The center of the dowel bar should be below the joint. If dowel placement deviates from the desired position, it is said to be misaligned

Rebar Placement

It is a general rule that reinforcements should be placed at the tension side at the bottom of the footing. In a square footing, rebars are placed uniformly in both directions. ACI code requires that the rebars be placed not more than 18 apart

Rebar Placement in Concrete Steps

Sonotube Placement

Place: Dig a hole to the desired depth. Place the tube in the hole, filling around the outside to secure. If the tube extends more than 2 feet above the ground line, provide additional support with a collar or wooden frame and side braces

Placement of Concrete

To provide durable concrete, it should be free of segregation and the mortar should be in close contact with the coarse aggregate, reinforcement, and any adjacent faces to which it is to be bonded. Concrete should be deposited, as nearly as practicable, in its final position

Cold Weather Concrete Placement

When “cold weather” conditions exist, concrete temperatures must be maintained at 50° f for at least two days if using high-early-strength or approved accelerated concrete. Three days of 50° f concrete temperature is required if regular concrete is used

Mass Concrete Placement

Mass placements are defined as placements with a least dimension greater than or equal to 5 ft., or designated on the plans.

Wire Mesh Placement in Concrete

Proper installation that provides maximum strength requires the mesh to be raised off the ground so that when the concrete sets, it’s in the lower third of the slab depth.

Concrete Consolidation Methods

The most widely used consolidation method is vibration. Vibration can be internal, external, or both. Vibration consists of subjecting freshly placed concrete to rapid vibratory impulses that liquefy the mortar and drastically reduce the internal friction between aggregate particles.

Consolidation of Concrete

Consolidation is the process of inducing a closer arrangement of the solid particles in freshly mixed concrete or mortar during placement by the reduction of voids, usually by vibration, centrifugation, rodding, tamping, or some combinations of these actions.

Grouting Material for Concrete

Grout is a composite material generally consisting of water, cement, and sand. It is typically used for filling voids under machines or other structural elements, sealing joints and openings in surfaces and reinforcing existing structures.

Injection Grouting Concrete Cracks

Injection grouting is the method of filling the cracks, open joints, voids, or honeycombs, in concrete or masonry structural members. This is done under pressure with a grout material that cures in place to produce the desired results like strengthening a structure and preventing water ingress

Pressure Grouting in Concrete

Pressure Grouting is the process of pumping a cement or chemical grout into soft or weak strata of soil or voids. This grout fills these voids, thus stabilizing and strengthening the soil. Pressure Grouting has many applications. One of these includes support for existing structures or where foundations have shifted

Jet Grouting Process

Jet grouting creates in situ columns of soilcrete (grouted soil), using a grouting monitor attached to the end of a drill stem. The jet grout monitor is advanced to the maximum treatment depth. Then high velocity jets (cement grout with optional water and air) are initiated from ports in the monitor.

Jet Grout Columns

Jet grout columns are typically formed from the bottom up. Jet Grouting is commonly used in conjunction with Soil Mixing or Slurry Trenching to complete a continuous barrier or soil-mixed monolith in areas with difficult or limited surface access, subsurface obstructions, or sensitive utility locations

Horizontal Jet Grouting

Horizontal jet grouting has proved to be an efficient and versatile technical solution and is increasingly being used for tunnelling in difficult soils, usually with high granulometry, presence of intense water flow and high hydraulic gradient.

Fracture Grouting

Compensation grouting, also known as fracture grouting, is the injection of a cement slurry grout, hydrofracturing soil, creating lenses. The lenses compact surrounding soil and then lift the overlying soil and structures

Permeation Grouting Method

Permeation grouting, also known as cement grouting or pressure grouting, fills cracks or voids in soil and rock and permeates coarse, granular soils with flowable particulate grouts to create a cemented mass.

Permeation Grouting Procedure

Permeation Grouting is the most common and oldest form of soil grouting. The technique consists of drilling a hole in the soil, inserting an injection pipe into the ground and then pumping any number of liquefied materials into the problem area.

Permeation Grouting

Compaction Grouting

Compaction grouting involves injecting a very stiff homogeneous grout mix under relatively high-pressures and at low injection rates to subsurface locations in pre-designed patterns in order to displace and compact soils.

Compaction Grouting Method

Compaction grouting involves the injection of a low slump, mortar grout to densify loose, granular soils and stabilise subsurface voids or sinkholes.

Compaction Grouting Procedure

The process involves injecting a stiff mortar- like grout into the ground to displace and compact the surrounding soil. During injection, the grout displaces the soil and forces the soil grains into tighter packing, expelling air and/or water out of the effected area, and reducing pore volume.

Vacuum Grouting

Vacuum grouting is a commonly used process in bridge concrete structures, and grouting of pores is a very critical link. The traditional grouting process will cause corrosion and component cracking after long-term use, which poses great safety hazards

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